The title race is not a foregone conclusion after all. Not only did Chelsea lose ground to Manchester City when Fabian Delph's late winner for Villa cut their lead to six points, they ended up short-handed as first Willian and then Ramires were dismissed, the latter incident provoking a heated exchange of opinions that led to José Mourinho being sent from the pitch in the final seconds.

Willian picked up a second yellow card for a rather soft foul on the goalscorer, but the stamp on Karim El Ahmadi that brought a straight red for Ramires was altogether more serious and brought the game to a bad-tempered conclusion, with players squaring up to each other in front of the Chelsea bench.

"I tried to speak to the referee, he refused to speak to me," said Mourinho, who has still never won at Villa Park. "I prefer not to speak about the referee or the sendings off. If I do that I will be in trouble."

Paul Lambert described Ramires's foul as "a shocker, a potential leg-breaker", but could not hide his satisfaction with the result. "We have seen some big moments here over the past two years, but that is probably the best," the Villa manager said. "The team performance was outstanding."

City have three games in hand so can now overhaul Chelsea if they keep winning. Their win at Hull was achieved by 10 men but Chelsea could not show the same drive and determination, even before their numbers were reduced.

Villa spent the first 10 minutes bemused by the movement and interchangeability of Chelsea's three-quarter line of Oscar, Willian and Eden Hazard as the visitors opened the game with businesslike intent, moving the ball around purposefully and always appearing to have a spare man. It was impressive to watch, yet Chelsea's approach work did not lead to any openings in front of goal, just speculative long shots from Willian and Oscar. Most of the attacking threat was being channelled through the industrious Hazard, and once Villa worked that out they settled down and began to put together some moves of their own.

Christian Benteke could not keep his header down when Delph crossed from the left, and El Ahmadi should have done better than waft wastefully over the bar with a decent shooting opportunity, though at least Villa boosted their own confidence by showing they knew the way to goal. When Benteke missed narrowly with a volley from the edge of the area that had Petr Cech scrambling just before half-time it was the closest the game had come to a goal, at least until Nemanja Matic bundled the ball over the Villa line a couple of minutes later, only to be recalled for handball by a linesman. It was hard to detect what the official had seen. It was far from an obvious handling offence, yet the player was slow to celebrate the goal as if he knew he might be pulled up. If that annoyed Mourinho, he was even more incensed on the stroke of the interval when Joe Bennett escaped with just a yellow card for bringing down Ramires in full flight when the Brazilian would have been through on goal. It was quite a long way out to be considered a clear goalscoring opportunity. Other players may have been able to come across and cover, though it would certainly have been a chance. Chris Foy's lenience brought Mourinho to his feet, waving an imaginary card, presumably a red one.

The visitors were dominating the game by the hour mark, with Villa rarely managing to cross the halfway line, though Chelsea's lack of conviction in front of goal was again highlighted by the directness the home side showed when they did come up with the occasional counterattack. Benteke was only inches wide after a one-two with Andreas Weimann in the area as once more Villa demonstrated they could soak up pressure and still threaten on the break.

Mourinho replaced Fernando Torres with Demba Ba midway through the second half in an attempt to bring more urgency to the Chelsea attack. Torres had not had one of his better games, losing the ball cheaply on more than one occasion, though the real problem seemed to be that while Hazard, Willian and Oscar could find each other with ease, even in tight situations in the penalty area, they could not find Torres or anyone else in a position to take a shy at goal.

Then, with 22 minutes remaining, Willian was gone and Chelsea were down to 10. The Brazilian was cautioned in the first half for a foul on El Ahmadi and received a second yellow, rather harshly in view of the trifling nature of the offence, for the slightest of tugs on Delph. That was all the encouragement Villa needed. Ba was a spectator, as Torres had been, and after Ron Vlaar had missed with a header from a corner, Delph put his side in front. Whether he applied the finish he intended was debatable, though he set up the goal by dispossessing Chelsea on halfway. If there was a bit of luck in the way he connected with Marc Albrighton's return pass to guide the ball past John Terry and Cech he probably deserved it. Benteke brought a save from Cech and Delph hit the bar in stoppage time.

Chelsea could have no complaints, especially after finishing with nine men and no manager.